/* coding.c
 *
 * Copyright (C) 2006-2026 wolfSSL Inc.
 *
 * This file is part of wolfSSL.
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335, USA
 */

#include <wolfssl/wolfcrypt/libwolfssl_sources.h>

#ifndef NO_CODING

#include <wolfssl/wolfcrypt/coding.h>
#ifndef NO_ASN
    #include <wolfssl/wolfcrypt/asn.h> /* For PEM_LINE_SZ */
#endif
#ifdef NO_INLINE
    #include <wolfssl/wolfcrypt/misc.h>
#else
    #define WOLFSSL_MISC_INCLUDED
    #include <wolfcrypt/src/misc.c>
#endif

enum {
    BAD         = 0xFF,  /* invalid encoding */
    PAD         = '=',
    BASE64_MIN  = 0x2B,
    BASE16_MIN  = 0x30
};


#ifndef BASE64_LINE_SZ
    #ifdef NO_ASN
        #define BASE64_LINE_SZ 64
    #else
        #define BASE64_LINE_SZ PEM_LINE_SZ
    #endif
#endif

#ifdef WOLFSSL_BASE64_DECODE

static WC_INLINE byte Base64_Char2Val_CT(byte c)
{
    int v;
    int smallEnd   = (int)c - 0x7b;
    int smallStart = (int)c - 0x61;
    int bigEnd     = (int)c - 0x5b;
    int bigStart   = (int)c - 0x41;
    int numEnd     = (int)c - 0x3a;
    int numStart   = (int)c - 0x30;
    int slashEnd   = (int)c - 0x30;
    int slashStart = (int)c - 0x2f;
    int plusEnd    = (int)c - 0x2c;
    int plusStart  = (int)c - 0x2b;

    v  = ((smallStart >> 8) ^ (smallEnd >> 8)) & (smallStart + 26 + 1);
    v |= ((bigStart   >> 8) ^ (bigEnd   >> 8)) & (bigStart   +  0 + 1);
    v |= ((numStart   >> 8) ^ (numEnd   >> 8)) & (numStart   + 52 + 1);
    v |= ((slashStart >> 8) ^ (slashEnd >> 8)) & (slashStart + 63 + 1);
    v |= ((plusStart  >> 8) ^ (plusEnd  >> 8)) & (plusStart  + 62 + 1);

    return (byte)(v - 1);
}

#ifndef BASE64_NO_TABLE

static
ALIGN64 const byte base64Decode_table[] = {    /* + starts at 0x2B */
/* 0x28:       + , - . / */                   62, BAD, BAD, BAD,  63,
/* 0x30: 0 1 2 3 4 5 6 7 */    52,  53,  54,  55,  56,  57,  58,  59,
/* 0x38: 8 9 : ; < = > ? */    60,  61, BAD, BAD, BAD, BAD, BAD, BAD,
/* 0x40: @ A B C D E F G */   BAD,   0,   1,   2,   3,   4,   5,   6,
/* 0x48: H I J K L M N O */     7,   8,   9,  10,  11,  12,  13,  14,
/* 0x50: P Q R S T U V W */    15,  16,  17,  18,  19,  20,  21,  22,
/* 0x58: X Y Z [ \ ] ^ _ */    23,  24,  25, BAD, BAD, BAD, BAD, BAD,
/* 0x60: ` a b c d e f g */   BAD,  26,  27,  28,  29,  30,  31,  32,
/* 0x68: h i j k l m n o */    33,  34,  35,  36,  37,  38,  39,  40,
/* 0x70: p q r s t u v w */    41,  42,  43,  44,  45,  46,  47,  48,
/* 0x78: x y z           */    49,  50,  51
                            };
#define BASE64DECODE_TABLE_SZ    (byte)(sizeof(base64Decode_table))

static WC_INLINE byte Base64_Char2Val_by_table(byte c)
{
#ifdef WC_CACHE_RESISTANT_BASE64_TABLE
    /* 80 characters in table.
     * 64 bytes in a cache line - first line has 64, second has 16
     */
    byte v;
    byte mask;

    c = (byte)(c - BASE64_MIN);
    mask = (byte)((((byte)(0x3f - c)) >> 7) - 1);
    /* Load a value from the first cache line and use when mask set. */
    v  = (byte)(base64Decode_table[ c & 0x3f        ] &   mask);
    /* Load a value from the second cache line and use when mask not set. */
    v |= (byte)(base64Decode_table[(c & 0x0f) | 0x40] & (~mask));

    return v;
#else
    return base64Decode_table[c - BASE64_MIN];
#endif
}

#endif /* !BASE64_NO_TABLE */

int Base64_SkipNewline(const byte* in, word32 *inLen,
  word32 *outJ)
{
    word32 len = *inLen;
    word32 j = *outJ;
    byte curChar;

    if (len == 0) {
        return BUFFER_E;
    }
    curChar = in[j];

    while (len > 1 && curChar == ' ') {
        /* skip whitespace in the middle or end of line */
        curChar = in[++j];
        len--;
    }
    if (len && (curChar == '\r' || curChar == '\n')) {
        j++;
        len--;
        if (curChar == '\r') {
            if (len) {
                curChar = in[j++];
                len--;
            }
        }
        if (curChar != '\n') {
            WOLFSSL_MSG("Bad end of line in Base64 Decode");
            return ASN_INPUT_E;
        }

        if (len) {
            curChar = in[j];
        }
    }
    while (len && curChar == ' ') {
        if (--len > 0) {
            curChar = in[++j];
        }
    }
    if (!len) {
        return BUFFER_E;
    }
    *inLen = len;
    *outJ = j;
    return 0;
}

#ifndef BASE64_NO_TABLE

int Base64_Decode_nonCT(const byte* in, word32 inLen, byte* out, word32* outLen)
{
    word32 i = 0;
    word32 j = 0;
    int ret;
    const byte maxIdx = BASE64DECODE_TABLE_SZ + BASE64_MIN - 1;

    while (inLen > 3) {
        int pad3 = 0;
        int pad4 = 0;
        byte b1, b2, b3;
        byte e1, e2, e3, e4;

        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            if (ret == WC_NO_ERR_TRACE(BUFFER_E)) {
                /* Running out of buffer here is not an error */
                break;
            }
            return ret;
        }
        e1 = in[j++];
        if (e1 == '\0') {
            break;
        }
        inLen--;
        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            return ret;
        }
        e2 = in[j++];
        inLen--;
        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            return ret;
        }
        e3 = in[j++];
        inLen--;
        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            return ret;
        }
        e4 = in[j++];
        inLen--;

        if (e3 == PAD)
            pad3 = 1;
        if (e4 == PAD)
            pad4 = 1;

        if (pad3 && !pad4)
            return ASN_INPUT_E;

        if (e1 < BASE64_MIN || e2 < BASE64_MIN || e3 < BASE64_MIN ||
                                                              e4 < BASE64_MIN) {
            WOLFSSL_MSG("Bad Base64 Decode data, too small");
            return ASN_INPUT_E;
        }

        if (e1 > maxIdx || e2 > maxIdx || e3 > maxIdx || e4 > maxIdx) {
            WOLFSSL_MSG("Bad Base64 Decode data, too big");
            return ASN_INPUT_E;
        }

        if (i + 1 + !pad3 + !pad4 > *outLen) {
            WOLFSSL_MSG("Bad Base64 Decode out buffer, too small");
            return BUFFER_E;
        }

        e1 = Base64_Char2Val_by_table(e1);
        e2 = Base64_Char2Val_by_table(e2);
        e3 = (byte)((e3 == PAD) ? 0 : Base64_Char2Val_by_table(e3));
        e4 = (byte)((e4 == PAD) ? 0 : Base64_Char2Val_by_table(e4));

        if (e1 == BAD || e2 == BAD || e3 == BAD || e4 == BAD) {
            WOLFSSL_MSG("Bad Base64 Decode bad character");
            return ASN_INPUT_E;
        }

        b1 = (byte)((e1 << 2) | (e2 >> 4));
        b2 = (byte)(((e2 & 0xF) << 4) | (e3 >> 2));
        b3 = (byte)(((e3 & 0x3) << 6) | e4);

        out[i++] = b1;
        if (!pad3)
            out[i++] = b2;
        if (!pad4)
            out[i++] = b3;
        else
            break;
    }

    /* If the output buffer has a room for an extra byte, add a null terminator */
    if (out && *outLen > i)
        out[i]= '\0';

    /* Note, *outLen won't reflect the optional terminating null. */
    *outLen = i;

    return 0;
}

#endif /* !BASE64_NO_TABLE */

int Base64_Decode(const byte* in, word32 inLen, byte* out, word32* outLen)
{
    word32 i = 0;
    word32 j = 0;
    int ret;

    while (inLen > 3) {
        int pad3 = 0;
        int pad4 = 0;
        byte b1, b2, b3;
        byte e1, e2, e3, e4;

        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            if (ret == WC_NO_ERR_TRACE(BUFFER_E)) {
                /* Running out of buffer here is not an error */
                break;
            }
            return ret;
        }
        e1 = in[j++];
        if (e1 == '\0') {
            break;
        }
        inLen--;
        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            return ret;
        }
        e2 = in[j++];
        inLen--;
        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            return ret;
        }
        e3 = in[j++];
        inLen--;
        if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
            return ret;
        }
        e4 = in[j++];
        inLen--;

        if (e3 == PAD)
            pad3 = 1;
        if (e4 == PAD)
            pad4 = 1;

        if (pad3 && !pad4)
            return ASN_INPUT_E;

        if (i + 1 + !pad3 + !pad4 > *outLen) {
            WOLFSSL_MSG("Bad Base64 Decode out buffer, too small");
            return BUFFER_E;
        }

        e1 = Base64_Char2Val_CT(e1);
        e2 = Base64_Char2Val_CT(e2);
        e3 = (byte)((e3 == PAD) ? 0 : Base64_Char2Val_CT(e3));
        e4 = (byte)((e4 == PAD) ? 0 : Base64_Char2Val_CT(e4));

        if (e1 == BAD || e2 == BAD || e3 == BAD || e4 == BAD) {
            WOLFSSL_MSG("Bad Base64 Decode bad character");
            return ASN_INPUT_E;
        }

        b1 = (byte)((e1 << 2) | (e2 >> 4));
        b2 = (byte)(((e2 & 0xF) << 4) | (e3 >> 2));
        b3 = (byte)(((e3 & 0x3) << 6) | e4);

        out[i++] = b1;
        if (!pad3)
            out[i++] = b2;
        if (!pad4)
            out[i++] = b3;
        else
            break;
    }

    /* If the output buffer has a room for an extra byte, add a null terminator */
    if (out && *outLen > i)
        out[i]= '\0';

    /* Note, *outLen won't reflect the optional terminating null. */
    *outLen = i;

    return 0;
}

#ifdef BASE64_NO_TABLE
int Base64_Decode_nonCT(const byte* in, word32 inLen, byte* out, word32* outLen) {
    return Base64_Decode(in, inLen, out, outLen);
}
#endif /* BASE64_NO_TABLE */

#endif /* WOLFSSL_BASE64_DECODE */

#if defined(WOLFSSL_BASE64_ENCODE)

static
const byte base64Encode[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
                              'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
                              'U', 'V', 'W', 'X', 'Y', 'Z',
                              'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
                              'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
                              'u', 'v', 'w', 'x', 'y', 'z',
                              '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                              '+', '/'
                            };


/* make sure *i (idx) won't exceed max, store and possibly escape to out,
 * raw means use e w/o decode,  0 on success */
static int CEscape(int escaped, byte e, byte* out, word32* i, word32 maxSz,
                  int raw, int getSzOnly)
{
    int    doEscape = 0;
    word32 needed = 1;
    word32 idx = *i;

    byte basic;
    byte plus    = 0;
    byte equals  = 0;
    byte newline = 0;

    if (raw)
        basic = e;
    else if (e < sizeof(base64Encode))
        basic = base64Encode[e];
    else
        return BAD_FUNC_ARG;

    /* check whether to escape. Only escape for EncodeEsc */
    if (escaped == WC_ESC_NL_ENC) {
        switch ((char)basic) {
            case '+' :
                plus     = 1;
                doEscape = 1;
                needed  += 2;
                break;
            case '=' :
                equals   = 1;
                doEscape = 1;
                needed  += 2;
                break;
            case '\n' :
                newline  = 1;
                doEscape = 1;
                needed  += 2;
                break;
            default:
                /* do nothing */
                break;
        }
    }

    /* check size */
    if ( (idx+needed) > maxSz && !getSzOnly) {
        WOLFSSL_MSG("Escape buffer max too small");
        return BUFFER_E;
    }

    /* store it */
    if (doEscape == 0) {
        if(getSzOnly)
            idx++;
        else
            out[idx++] = basic;
    }
    else {
        if(getSzOnly)
            idx+=3;
        else {
            out[idx++] = '%';  /* start escape */

            if (plus) {
                out[idx++] = '2';
                out[idx++] = 'B';
            }
            else if (equals) {
                out[idx++] = '3';
                out[idx++] = 'D';
            }
            else if (newline) {
                out[idx++] = '0';
                out[idx++] = 'A';
            }
        }
    }
    *i = idx;

    return 0;
}


/* internal worker, handles both escaped and normal line endings.
   If out buffer is NULL, will return sz needed in outLen */
static int DoBase64_Encode(const byte* in, word32 inLen, byte* out,
                           word32* outLen, int escaped)
{
    int    ret = 0;
    word32 i = 0,
           j = 0,
           n = 0;   /* new line counter */

    int    getSzOnly = (out == NULL);

    word32 outSz = (inLen + 3 - 1) / 3 * 4;
    word32 addSz = (outSz + BASE64_LINE_SZ - 1) / BASE64_LINE_SZ;  /* new lines */

    if (escaped == WC_ESC_NL_ENC)
        addSz *= 3;   /* instead of just \n, we're doing %0A triplet */
    else if (escaped == WC_NO_NL_ENC)
        addSz = 0;    /* encode without \n */

    outSz += addSz;

    /* if escaped we can't predetermine size for one pass encoding, but
     * make sure we have enough if no escapes are in input
     * Also need to ensure outLen valid before dereference */
    if (!outLen || (outSz > *outLen && !getSzOnly)) return BAD_FUNC_ARG;

    while (inLen > 2) {
        byte b1 = in[j++];
        byte b2 = in[j++];
        byte b3 = in[j++];

        /* encoded idx */
        byte e1 = b1 >> 2;
        byte e2 = (byte)(((b1 & 0x3) << 4) | (b2 >> 4));
        byte e3 = (byte)(((b2 & 0xF) << 2) | (b3 >> 6));
        byte e4 = b3 & 0x3F;

        /* store */
        ret = CEscape(escaped, e1, out, &i, *outLen, 0, getSzOnly);
        if (ret != 0) break;
        ret = CEscape(escaped, e2, out, &i, *outLen, 0, getSzOnly);
        if (ret != 0) break;
        ret = CEscape(escaped, e3, out, &i, *outLen, 0, getSzOnly);
        if (ret != 0) break;
        ret = CEscape(escaped, e4, out, &i, *outLen, 0, getSzOnly);
        if (ret != 0) break;

        inLen -= 3;

        /* Insert newline after BASE64_LINE_SZ, unless no \n requested */
        if (escaped != WC_NO_NL_ENC && (++n % (BASE64_LINE_SZ/4)) == 0 && inLen) {
            ret = CEscape(escaped, '\n', out, &i, *outLen, 1, getSzOnly);
            if (ret != 0) break;
        }
    }

    /* last integral */
    if (inLen && ret == 0) {
        int twoBytes = (inLen == 2);

        byte b1 = in[j++];
        byte b2 = (twoBytes) ? in[j++] : 0;

        byte e1 = b1 >> 2;
        byte e2 = (byte)(((b1 & 0x3) << 4) | (b2 >> 4));
        byte e3 = (byte)((b2 & 0xF) << 2);

        ret = CEscape(escaped, e1, out, &i, *outLen, 0, getSzOnly);
        if (ret == 0)
            ret = CEscape(escaped, e2, out, &i, *outLen, 0, getSzOnly);
        if (ret == 0) {
            /* third */
            if (twoBytes)
                ret = CEscape(escaped, e3, out, &i, *outLen, 0, getSzOnly);
            else
                ret = CEscape(escaped, '=', out, &i, *outLen, 1, getSzOnly);
        }
        /* fourth always pad */
        if (ret == 0)
            ret = CEscape(escaped, '=', out, &i, *outLen, 1, getSzOnly);
    }

    if (ret == 0 && escaped != WC_NO_NL_ENC)
        ret = CEscape(escaped, '\n', out, &i, *outLen, 1, getSzOnly);

    if (i != outSz && escaped != 1 && ret == 0)
        return ASN_INPUT_E;
/* If the output buffer has a room for an extra byte, add a null terminator */
    if (out && *outLen > i)
        out[i]= '\0';

    *outLen = i;

    if (ret == 0)
        return getSzOnly ? WC_NO_ERR_TRACE(LENGTH_ONLY_E) : 0;

    return ret;
}


/* Base64 Encode, PEM style, with \n line endings */
int Base64_Encode(const byte* in, word32 inLen, byte* out, word32* outLen)
{
    return DoBase64_Encode(in, inLen, out, outLen, WC_STD_ENC);
}


/* Base64 Encode, with %0A escaped line endings instead of \n */
int Base64_EncodeEsc(const byte* in, word32 inLen, byte* out, word32* outLen)
{
    return DoBase64_Encode(in, inLen, out, outLen, WC_ESC_NL_ENC);
}

int Base64_Encode_NoNl(const byte* in, word32 inLen, byte* out, word32* outLen)
{
    return DoBase64_Encode(in, inLen, out, outLen, WC_NO_NL_ENC);
}

#endif /* WOLFSSL_BASE64_ENCODE */


#ifdef WOLFSSL_BASE16

static
const ALIGN64 byte hexDecode[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
                           BAD, BAD, BAD, BAD, BAD, BAD, BAD,
                           10, 11, 12, 13, 14, 15,  /* upper case A-F */
                           BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
                           BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
                           BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
                           BAD, BAD,  /* G - ` */
                           10, 11, 12, 13, 14, 15   /* lower case a-f */
                         };  /* A starts at 0x41 not 0x3A */

int Base16_Decode(const byte* in, word32 inLen, byte* out, word32* outLen)
{
    word32 inIdx  = 0;
    word32 outIdx = 0;

    if (in == NULL || out == NULL || outLen == NULL)
        return BAD_FUNC_ARG;

    if (inLen == 1 && *outLen && in) {
        byte b = (byte)(in[inIdx++] - BASE16_MIN);  /* 0 starts at 0x30 */

        /* sanity check */
        if (b >=  sizeof(hexDecode)/sizeof(hexDecode[0]))
            return ASN_INPUT_E;

        b  = hexDecode[b];

        if (b == BAD)
            return ASN_INPUT_E;

        out[outIdx++] = b;

        *outLen = outIdx;
        return 0;
    }

    if (inLen % 2)
        return BAD_FUNC_ARG;

    if (*outLen < (inLen / 2))
        return BUFFER_E;

    while (inLen) {
        byte b  = (byte)(in[inIdx++] - BASE16_MIN);  /* 0 starts at 0x30 */
        byte b2 = (byte)(in[inIdx++] - BASE16_MIN);

        /* sanity checks */
        if (b >=  sizeof(hexDecode)/sizeof(hexDecode[0]))
            return ASN_INPUT_E;
        if (b2 >= sizeof(hexDecode)/sizeof(hexDecode[0]))
            return ASN_INPUT_E;

        b  = hexDecode[b];
        b2 = hexDecode[b2];

        if (b == BAD || b2 == BAD)
            return ASN_INPUT_E;

        out[outIdx++] = (byte)((b << 4) | b2);
        inLen -= 2;
    }

    *outLen = outIdx;
    return 0;
}

static
const ALIGN64 byte hexEncode[] = { '0', '1', '2', '3', '4', '5', '6', '7',
                                   '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};

int Base16_Encode(const byte* in, word32 inLen, byte* out, word32* outLen)
{
    word32 outIdx = 0;
    word32 i;

    if (in == NULL || out == NULL || outLen == NULL)
        return BAD_FUNC_ARG;

    if (*outLen < (2 * inLen))
        return BAD_FUNC_ARG;

    for (i = 0; i < inLen; i++) {
        byte hb = in[i] >> 4;
        byte lb = in[i] & 0x0f;

        hb = hexEncode[hb];
        lb = hexEncode[lb];

        out[outIdx++] = hb;
        out[outIdx++] = lb;
    }

    /* If the output buffer has a room for an extra byte, add a null terminator */
    if (*outLen > outIdx)
        out[outIdx++]= '\0';

    *outLen = outIdx;
    return 0;
}

#endif /* WOLFSSL_BASE16 */

#endif /* !NO_CODING */
